Colloidal-type indicators and displays have been proposed, and are well known, in which electrodes are supported on electrode substrates or carriers and, when selectively energized, provide displays in the form of bars, dots or the like which, when located adjacent each other, may provide alphanumeric characters, symbols, and the like. It has also been proposed to mask display zones which are not to contain information, for example by external masks, applied to external glass surfaces of the displays. The glasses used in the colloidal indicator devices have a minimum thickness for mechanical strength and, thus, it is very difficult to apply the masks precisely following segmental areas of the display while insuring parallax-free reading. Colloidal displays which are so masked, during their manufacture, require an additional processing step which increases the cost of masked display systems. Reading of the display is also impaired by the "edge effect" which occurs at the edges of controlled segments.
These edge effects limit the lifetime of the systems and arise during operation thereof. The edge effects are caused by enrichment of suspended particles of the colloidal liquid between the electrodes at the edges thereof at the side of the electrodes, with a decrease at the side of the glass. The result is a light, poorly absorbing edge about the respective segment when no control voltage is applied anymore.